Typically the ideal location for first detecting a leak adjacent to a machine is in an difficult to access location or area, thus placement of an automated leak detection apparatus in its ideal location will hasten the timeliness of a useful perceptible output from the leak detection apparatus to minimize damage to either or both the machine or surrounding structure. Wherein normally without the presence of any type of leak detection apparatus, a small liquid leakage from a machine, say for instance hidden underneath a large heavy ice making machine (that is rarely moved) that has a low volumetric flowrate leak or in other words a seeping leak can cause significant damage to the machine and/or surrounding adjacent structure prior to being detected. Unfortunately, the ice machine will continue to work perfectly during its small leakage phase thus not alerting a user to the presence of the slight leakage condition.
Also, this situation can continue for quite some time until extensive damage has occurred in the hidden machine portions and/or support structure, wherein at some later in time point the structural damage eventually becomes obvious, wherein the structural damage from the liquid seepage is more excessive than it should be. Thus, the result is that the support structure suffers damage that is hidden from view in addition to the leaked fluid, typically water or even worse a fluid that is toxic or chemical in nature that could risk further safety, electrical risk, or environmental harm. Further for the benefit of the machine, a plurality of leak detection apparatus could be utilized to better pin point the source location of the fluid leak thus providing for a quicker diagnosis of the exact leak source to more efficiently fix the leaking machine.
Thus, the key issues for the leak detection apparatus involve, small space or size requirements for the apparatus, as the specific placement location for the apparatus may be in a confined area with difficult accessibility, a further issue in the leak detection apparatus is the sensitivity of generating a perceptible output from a very low liquid leakage flowrate, usually in the range of about 1 milliliter per minute in volume or approximately 1 drop every 10 seconds, which can be a challenge to monitor effectively. Another issue for the leak detection apparatus is in the perceptible output, such that an alarm or signal can be generated to result in an automated sequence of events such as deactivating the machine or shutting off the liquid supply to the machine, in conjunction with remote signals to a data acquisition system for logging events.
The prior art has recognized the importance of low volumetric flowrate fluid leak detection in remote or difficult to access areas, so there are a number of approaches to this problem of low fluid flow rates for liquid leak detection. Starting with United States Patent Publication Number 2006/0244616 to Hill, disclosed is a water leakage monitoring and response system adapted for residential and commercial use. The Hill system is designed to detect water leaks within a building that accumulate on a floor or adjacent to a baseboard perimeter near floor level. The Hill system comprises a flexible, elongated, moisture sensing strip for placement on a floor or adjacent a baseboard or plumbing fixture, comprising flexible upper and lower wires separated by a water permeable, nonconductive layer, and nonconductive upper and lower layers that extend away from the wires to form margins for attaching the strip to a surface and for wicking moisture toward the wires.
The Hill unit also provides an audible warning of low-battery power and can signal a home security system when a leak is detected, see page 1, paragraph 12, and the abstract. Hill has for the actual leak detection, a pair of conductors utilized that are separated by the water permeable material, wherein the water permeable material becomes conductive when it is saturated with liquid, the water permeable material can have extended margins that can act as wicks for bringing liquid to the area of the water permeable material between the wires. Hill teaches another embodiment that includes a grid of conductive material, such as aluminum screen material sandwiched between two pads for coverage of a more square area for leak detection, such as a floor as opposed to a more longitudinal, i.e. pipe based leak detection system. Further taught by Hill is a non permeable base sheet material that can retain the leaked liquid, similar to a diaper, for a limited time period or a limited amount of liquid volume, while the leak signal is communicated while simultaneously protecting the underlying surface from liquid seepage.
Hill has no teaching specific to details of the wicking process or unique configurations of the permeable material to enhance liquid leak detection for specific leak monitoring situations, such as curved tubing, and the like, as Hill is primarily for horizontal linear floor and baseboard structures for overall liquid leak detection. Further, Hill would require a larger adjacent planar area below the machine that needs leak detection for the leak detection system to work properly, thus Hill would have difficulty if the machine were mounted in an area that didn't provide an adjacent planar surface, such as mounting the machine within a cabinet grouping.
Further continuing in the prior art in U.S. Pat. No. 6,310,555 to Stern, disclosed is a battery-powered liquid and humidity detection and alarm system comprising a transistorized moisture sensor, alarm system, and low-battery alert. The sensor aspect of the Stern device is in the form of an outer and inner ring of copper coils, and is positioned in place by a rubber or similarly flexible strip. The presence of moisture on the sensor element causes a forward bias in the transistor, triggering an audible alarm or flashing light. The sensor in Stern is sensitive as to detect unwarranted moisture as the presence of human sweat or several molecules of water droplets in contact with the sensor element. The alarm in Stern is also capable of being wired to a remote radio-operated control unit, and a land based phone line to notify a plumber, see Column 2, lines 49-61. Stern also uses changes in circuit leakage currents which correspond to a voltage change for generating a signal resulting from the presence of moisture adjacent to the conductors.
Continuing in the leakage detection arts, in U.S. Pat. No. 7,398,676 to Lim et al. disclosed is a leak sensor and leak sensing system which may include a liquid sensing member capable of sensing and indicating the presence of a liquid leakage. In Lim et al., two or more wires may further be combined within the liquid sensing member and the leak sensor may include a film that is capable of visually indicating the presence of a specific liquid type that is leaked from a pipe through which the liquid flows, i.e. in the form of litmus paper. The film in Lim et al., preferably encircles a circumference of the pipe and at least two wires may be incorporated in the film, with the wires being are preferably configured to be short-circuited by contact with the liquid leaked from the pipe. The leak sensing system in Lim et al., may include a plurality of liquid sensors with the liquid sensors being preferably arranged to encircle a pipe through which a liquid flows at multiple locations along the pipe where leaks are likely to occur, see Column 2, lines 5-28.
Further, in the leakage detection art field, in U.S. Pat. No. 5,686,893 to Jeon, disclosed is a water leakage detecting apparatus for a water purifier by which the purifying operation can be stopped to thereby generate an alarm for enabling an immediate remedial action, and at the same time, to make the water purifier hygienically and accident-free, where water leakage occurs due to poor sealing of connecting pipes through which the water passes and clogging of an overflow pipe for preventing proper drainage of overflowing water. In Jeon, this objective can be accomplished by a water leakage detecting apparatus of a water purifier employing a storage tank in order to store water purified in a pre-processing filter, membrane, and a post-processing filter.
The apparatus in Jeon comprises, a water leakage detecting means for detecting water leakage outside of the storage tank in water utilizing a water leakage tray pan, control means for receiving a leakage detecting signal detected by the water leakage detecting means to thereby control overall water purifying operations. A display means in also included in Jeon for receiving a control signal output from the control means according to the leakage detecting signal detected by the leakage detecting means to thereby indicate whether or not there has occurred a leakage and an alarm generating means for receiving the control signal generated from the control means according to the leakage detecting signal detected by the leakage detecting means to thereby generate an alarm for informing an occurrence of water leakage, see Column 2, lines 36-63. As to the water sensor 63 in Jeon, there is no detailed teaching as to the function of the sensor 63 other than its power supply circuitry that includes R1, R2, and C1, as shown in FIG. 6.
Next in looking at the prior art for liquid leakage detection, in U.S. Pat. No. 7,218,237 to Kates, disclosed is a method and apparatus for detecting water leaks being a tray pan type arrangement as in Jeon disclosed above, wherein the liquid rising level is detected to indicate leakage. The system in Kates includes one or more intelligent sensor units and a base unit that can communicate with the sensor units. When one or more of the sensor units in Kates detects an anomalous condition (e.g., smoke, fire, water, etc.) the sensor unit communicates with the base unit and provides data regarding the anomalous condition. The base unit in Kates can contact a supervisor or other responsible person by a plurality of techniques, such as, telephone, pager, cellular telephone, internet (and/or local area network), etc.
In one embodiment in Kates, one or more wireless repeaters are used between the sensor units and the base unit to extend the range or the system and to allow the base unit to communicate with a larger number of sensors, see Column 1, lines 41-56. In Kates, there is no specific teaching as to the detailed workings of the moisture or water level sensor, being more of a system combination of gas and temperature level sensing and indication. Further in Kates, the tray pan arrangement would not likely be acceptable for built-in type machines that would desirably require leak detection, or for machines that are attached to cabinetry or that have custom matching front panels, wherein the clearances as between the machine and the adjoining structure are minimal, being as small as 1/16 of an inch. In addition, if the machine needing leak detection were elevated above the floor surface, i.e. mounting within cabinetry, a tray would not be easily possible, much the same as the problem in Hill previously described.
What is needed is a leak detection apparatus that is adaptable to being functional in sensing presence of a liquid in an area based upon very low liquid flow rates with the leak detection apparatus including a first flexible member that is constructed of an electrically conductive material that is in an normally open circuit state and a second flexible member also constructed of an electrically conductive material that is in an normally open circuit state. Also included in the leak detection apparatus would be a liquid wicking permeable surrounding sidewall that is adjacent to the first and second flexible members, with the liquid permeable surrounding sidewall being constructed of a non electrically conductive material, wherein operationally the liquid wicking permeable surrounding sidewall becomes electrically conductive when the liquid is present in the liquid wicking permeable surrounding sidewall, facilitating the first and second flexible members to move from the normally open circuit state to a closed circuit state thus facilitating that the perceptible output be made for the liquid leakage occurring to alert a maintenance operation for remedying the leakage. Further, a liquid permeable planar web reinforcing element that is oriented adjacent to the liquid wicking permeable surrounding sidewall and an additional liquid channeling structure and absorption material to better facilitate low flow rate liquid leakage directed to the first and second flexible members to facilitate the perceptible output of the liquid leakage.